It would be interesting to try and make a graph of the product lines / companies in this space. I.e. HP started off doing test equipment, and back in the 90s spun that division and everything not related to computers/storage/printers to Agilent. Agilent has since spun off:
* Phillips Medical Systems: health care
* Avago: Semiconductors
* Verigy: Semiconductor test
* Keysight: Test equipment
+ Probably more I don't know about due to acquisitions.